1. Field of the Invention
The present invention generally relates to digital television technologies, and more particularly to a method and system for generating a packet identifier table from a received transport stream.
2. Description of the Related Art
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Compared to an analog television, a digital television (“DTV”) is capable of broadcasting a higher number of programs with higher-quality video and audio content. A broadcaster source usually compresses and multiplexes the video and audio contents of an original program with other programs and system information that is needed to recover the original programs. The multiplexed signal is then modulated and transmitted in the form of transport stream packets to a subscriber's home. A receiver device at the subscriber's home demodulates the signal to recover the multiplexed digital streams, extracts the program of interest, and decodes the compressed audio and video contents for presentation on a display device.
There are a variety of methods for encoding and delivering these digital television programs. To promote the development of interoperable components from different manufacturers, the Moving Picture Experts Group (“MPEG”) has developed several different international standards. The MPEG-2 standard is one of these standards particularly applicable for delivering digital television programs. According to the MPEG-2 standard, a transport stream typically consists of multiple packetized elementary streams (“PES”) containing compressed audio and video data that are multiplexed with program-specific information (“PSI”) that defines the content of the transport stream. The program-specific information usually includes a number of program information tables that provide a mapping between each type of data contained in the transport stream packets and a corresponding packet identifier (“PID”) that labels all packets conveying the associated type of data. The program information tables therefore allow the receiver device to identify which transport stream packets contain audio and video data, as well as other types of data that may be conveyed in the transport stream packets.
In a conventional receiver device, an initial recovery of the program information tables is thus usually required. Based on the program information tables, the receiver device can then filter the correct transport stream packets to restore the audio and video contents of a program of interest. However, it is possible that sometimes the program information tables cannot be found or are not correctly recovered. In these situations, the conventional receiver device is usually incapable to further process the transport stream packets to restore the audio and video content.
What is needed in the art is thus a method and system that addresses at least the problems set forth above and allows a receiver device to still operate correctly to restore audio and video contents in the event of failing to recover program information tables from received transport stream packets.